This is a walking mechanism based on the Klann linkage, seen elsewhere in form of spider-like creature. Now instead of making one set of linkage for each leg, I copy the movement of the leg tip to the back side and connect them using two bars, here the foot and the connector. The wide foot surface would enable it to walk over soft terrain like sand, where common pointed legs could be stuck in. This set consists of 2 feet with 180 degree phase difference. With the dc motor, the speed is about 2 steps per second.
Walking demo video: https://youtu.be/mHIyUTuQcdY
There are 2 hole sizes, 3.2mm for passing of 3mm screw and 2.8mm for tapping.